提交 b936887e 编写于 作者: J Johannes Weiner 提交者: Linus Torvalds

mm: workingset: turn shadow node shrinker bugs into warnings

When the shadow page shrinker tries to reclaim a radix tree node but
finds it in an unexpected state - it should contain no pages, and
non-zero shadow entries - there is no need to kill the executing task or
even the entire system.  Warn about the invalid state, then leave that
tree node be.  Simply don't put it back on the shadow LRU for future
reclaim and move on.

Link: http://lkml.kernel.org/r/20161117191138.22769-4-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 59749e6c
无相关合并请求
......@@ -418,23 +418,27 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
* no pages, so we expect to be able to remove them all and
* delete and free the empty node afterwards.
*/
BUG_ON(!workingset_node_shadows(node));
BUG_ON(workingset_node_pages(node));
if (WARN_ON_ONCE(!workingset_node_shadows(node)))
goto out_invalid;
if (WARN_ON_ONCE(workingset_node_pages(node)))
goto out_invalid;
for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
if (node->slots[i]) {
BUG_ON(!radix_tree_exceptional_entry(node->slots[i]));
if (WARN_ON_ONCE(!radix_tree_exceptional_entry(node->slots[i])))
goto out_invalid;
if (WARN_ON_ONCE(!mapping->nrexceptional))
goto out_invalid;
node->slots[i] = NULL;
workingset_node_shadows_dec(node);
BUG_ON(!mapping->nrexceptional);
mapping->nrexceptional--;
}
}
BUG_ON(workingset_node_shadows(node));
if (WARN_ON_ONCE(workingset_node_shadows(node)))
goto out_invalid;
inc_node_state(page_pgdat(virt_to_page(node)), WORKINGSET_NODERECLAIM);
if (!__radix_tree_delete_node(&mapping->page_tree, node))
BUG();
__radix_tree_delete_node(&mapping->page_tree, node);
out_invalid:
spin_unlock(&mapping->tree_lock);
ret = LRU_REMOVED_RETRY;
out:
......
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